ClonaCell™-HY PEG

Overview

ClonaCell™-HY Hybridoma Kit contains media and reagents for all steps in hybridoma development and monoclonal antibody production. The ClonaCell™-HY method uses a methylcellulose-based semi-solid selective medium to combine hybridoma selection and cloning into one step. Individual parental hybridoma clones and their progeny remain localized together in the semi-solid medium as they grow to form distinct colonies. This prevents the loss of rare clones by overgrowth from faster-growing cells, as can occur during selection in a liquid medium. The hybridoma colonies can be easily picked from the semi-solid medium by manual or robotic methods and dispersed into a liquid growth medium for screening and expansion. This kit has been verified for use in mouse and rat hydridoma development and monoclonal antibody production and reportedly is compatible for production, cloning, and expansion of hybridomas using lymphocytes from a variety of host animals including human, mouse, rat, and hamster.

Advantages:

• Time savings: Hybridoma selection and cloning are combined into one step
• Resource savings: Single cell-derived hybridomas form visible discrete colonies in semi-solid medium, and are easy to pick and screen, and transfer to liquid medium for expansion
• Cloning efficiency: Individual cells are suspended and immobilized in semi-solid medium, preventing loss of rare, high-producing clones by overgrowth

Frequently Asked Questions

Why is there HT (hypoxanthine, thymidine) in Medium E?

Hybridomas are selected using HAT (hypoxanthine, aminopterin, thymidine). Aminopterin blocks the de novo pathway for synthesizing nucleotide precursors for DNA synthesis. The inhibition of the de novo pathway can persist even after the cells are removed from selection. Hypoxanthine and thymidine (HT) provide the necessary nucleotide precursors for hybridoma cells to synthesize DNA using the salvage pathway. Once the cells are growing well in Medium E, they can be gradually switched to Medium A or another medium without HT.

Is the serum in ClonaCell™-HY media heat inactivated?

Yes, all serum used in ClonaCell™-HY media is heat inactivated.

Is there any IgG in clonacell™-HY media?

While we don't add IgG to the ClonaCell™-HY media, we do add serum, which contains an undefined amount of IgG. We selectively use serum lots with low IgG levels in the production of ClonaCell™-HY media, however, levels vary from lot to lot. IgG levels in a specific lot of ClonaCell™-HY medium are available in the lot-specific Certificate of Analysis.

Are there antibiotics in ClonaCell™-HY media?

These products contain gentamycin rather than penicillin/streptomycin/amphotericin B, because gentamycin is more stable and is a broad spectrum antibiotic that is non-toxic to most mammalian cells in culture.

What is the optimal number of colonies per plate?

We recommend 50-150 colonies per plate. An average fusion will result in approximately 1000 colonies per fusion (approx. 100 colonies per plate). Even if the average number of colonies per plate approaches 300, there should still be enough separation between colonies to pick easily.

Why do I have to put my fused cells into liquid medium overnight? Why can't I just plate directly into Medium D?

We recommend waiting up to 24 hours so that all of the fused cells can go through one cell cycle. This will ensure they have a chance to express HPRT (hypoxanthine guanine phosphoribosyltransferase), the enzyme necessary to survive in the presence of aminopterin (present in Medium D). Additionally, fused cells are very fragile immediately after fusion. Waiting a day before mixing the cells with the methylcellulose will improve their survival. Although it is not recommended, fused cells may be plated on the same day as fusion, but the cells should be allowed to recover for several hours in ClonaCell™-HY Medium C prior to plating.

What myeloma and mouse strains should I use?

Myeloma: There are at least two common myeloma cell lines used to generate hybridomas - SP2/0 and P3X63Ag8.683. Both are available from ATCC. Researchers should ensure that the myeloma line is from a reliable source and is negative for mycoplasma. Mycoplasma contamination of the myeloma line can result in decreased efficiency of hybridoma formation. Mouse: We suggest using BALB/c splenocytes and parental myeloma cells of BALB/c for the following reasons: they are highly immune reactive, well characterized and myeloma cells are available from the same genetic strain. Other mouse strains, however, are also compatible with cloning in ClonaCell™-HY media.

Can I grow human/rat/T cell hybridomas in ClonaCell™-HY?

Although we have not tried to generate human, rat or T cell hybridomas during in-house testing, these experiments are expected to be successful using ClonaCell™-HY. The researcher would need to ensure that the cell lines used in the fusion are sensitive to HAT selection and grow well in methylcellulose-based medium.

There are very few colonies growing in my Medium D. Why?

Low numbers of colonies is generally a result of low fusion efficiency, which can have many causes. The fusion efficiency can be affected by the presence of serum during fusion, the presence of mycoplasma, low viability of cells, overexposure to polyethylene glycol or slow-growing myeloma cells prior to fusion.

Why does the ClonaCell™-HY manual suggest two different methods for fusion (A or B)? Can one expect better results with one method over the other?

Which method chosen is a personal preference and there should not be significant differences in efficiency. Method B is faster and has less steps, but Method B requires you to remove all the PEG before the cells are diluted, so you will risk aspirating cells if not very careful. With Method A, you dilute the PEG with Medium B, so you have less opportunity to lose cells.

Why does the ClonaCell™-HY manual suggest two different methods for fusion (A or B)? Can one expect better results with one method over the other?

A: Which method chosen is a personal preference and there should not be significant differences in efficiency. Method B is faster and has less steps, but Method B requires you to remove all the PEG before the cells are diluted, so you will risk aspirating cells if not very careful. With Method A, you dilute the PEG with Medium B, so you have less opportunity to lose cells.

Once I pick the colonies and grow the cells in plates, will the residual methylcellulose interfere with characterization? For example, will I have problems doing an ELISA?

There will likely be some residual methylcellulose contamination when colonies are picked and transferred to the 96-well plate with the liquid growth medium. The concentration of methylcellulose, however, should be low enough that it should not interfere with most assays.

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Product Applications

This product is designed for use in the following research area(s) as part of the highlighted workflow stage(s). Explore these workflows to learn more about the other products we offer to support each research area.

Abstract

Palivizumab was the first antiviral monoclonal antibody (mAb) approved for therapeutic use in humans, and remains a prophylactic treatment for infants at risk for severe disease because of respiratory syncytial virus (RSV). Palivizumab is an engineered humanized version of a murine mAb targeting antigenic site II of the RSV fusion (F) protein, a key target in vaccine development. There are limited reported naturally occurring human mAbs to site II; therefore, the structural basis for human antibody recognition of this major antigenic site is poorly understood. Here, we describe a nonneutralizing class of site II-specific mAbs that competed for binding with palivizumab to postfusion RSV F protein. We also describe two classes of site II-specific neutralizing mAbs, one of which escaped competition with nonneutralizing mAbs. An X-ray crystal structure of the neutralizing mAb 14N4 in complex with F protein showed that the binding angle at which human neutralizing mAbs interact with antigenic site II determines whether or not nonneutralizing antibodies compete with their binding. Fine-mapping studies determined that nonneutralizing mAbs that interfere with binding of neutralizing mAbs recognize site II with a pose that facilitates binding to an epitope containing F surface residues on a neighboring protomer. Neutralizing antibodies, like motavizumab and a new mAb designated 3J20 that escape interference by the inhibiting mAbs, avoid such contact by binding at an angle that is shifted away from the nonneutralizing site. Furthermore, binding to rationally and computationally designed site II helix-loop-helix epitope-scaffold vaccines distinguished neutralizing from nonneutralizing site II antibodies.

Antiviral Research 2016 NOV

An influenza A virus (H7N9) anti-neuraminidase monoclonal antibody with prophylactic and therapeutic activity in vivo

Abstract

Zoonotic A(H7N9) avian influenza viruses emerged in China in 2013 and continue to be a threat to human public health, having infected over 800 individuals with a mortality rate approaching 40&percnt;. Treatment options for people infected with A(H7N9) include the use of neuraminidase (NA) inhibitors. However, like other influenza viruses, A(H7N9) can become resistant to these drugs. The use of monoclonal antibodies is a rapidly developing strategy for controlling influenza virus infection. Here we generated a murine monoclonal antibody (3c10-3) directed against the NA of A(H7N9) and show that prophylactic systemic administration of 3c10-3 fully protected mice from lethal challenge with wild-type A/Anhui/1/2013 (H7N9). Further, post-infection treatment with a single systemic dose of 3c10-3 at either 24, 48 or 72 h post A(H7N9) challenge resulted in both dose- and time-dependent protection of up to 100&percnt; of mice, demonstrating therapeutic potential for 3c10-3. Epitope mapping revealed that 3c10-3 binds near the enzyme active site of NA, and functional characterization showed that 3c10-3 inhibits the enzyme activity of NA and restricts the cell-to-cell spread of the virus in cultured cells. Affinity analysis also revealed that 3c10-3 binds equally well to recombinant NA of wild-type A/Anhui/1/2013 and to a variant NA carrying a R289K mutation known to infer NAI resistance. These results suggest that 3c10-3 has the potential to be used as a therapeutic to treat A(H7N9) infections either as an alternative to, or in combination with, current NA antiviral inhibitors.

Abstract

It has been proposed that the ancestral fungus was mating competent and homothallic. However, many mating-competent fungi were initially classified as asexual because their mating capacity was hidden behind layers of regulation. For efficient in vitro mating, the essentially obligate diploid ascomycete pathogen Candida albicans has to change its mating type locus from heterozygous MTL a /α to homozygous MTL a / a or MTL α/α and then undergo an environmentally controlled epigenetic switch to the mating-competent opaque form. These requirements greatly reduce the potential for C. albicans mating. Deletion of the Yci1 domain gene OFR1 bypasses the need for C. albicans cells to change the mating type locus from heterozygous to homozygous prior to switching to the opaque form and mating and allows homothallic mating of MTL heterozygous strains. This bypass is carbon source dependent and does not occur when cells are grown on glucose. Transcriptional profiling of ofr1 mutant cells shows that in addition to regulating cell type and mating circuitry, Ofr1 is needed for proper regulation of histone and chitin biosynthesis gene expression. It appears that OFR1 is a key regulator in C. albicans and functions in part to maintain the cryptic mating phenotype of the pathogen.

Abstract

Small Kinetochore-Associated Protein (SKAP)/Kinastrin is a multifunctional protein with proposed roles in mitosis, apoptosis and cell migration. Exact mechanisms underlying its activities in these cellular processes are not completely understood. SKAP is predicted to have different isoforms, however, previous studies did not differentiate between them. Since distinct molecular architectures of protein isoforms often influence their localization and functions, this study aimed to examine the expression profile and functional differences between SKAP isoforms in human and mouse. Analyses of various human tissues and cells of different origin by RT-PCR, and by Western blotting and immunocytochemistry applying newly generated anti-SKAP monoclonal antibodies revealed that human SKAP exists in two protein isoforms: ubiquitously expressed SKAP16 and testis/sperm-specific SKAP1. In mouse, SKAP1 expression is detectable in testis at 4 weeks postnatally, when the first wave of spermatogenesis in mice is complete and the elongated spermatids are present in the testes. Furthermore, we identified Pontin as a new SKAP1 interaction partner. SKAP1 and Pontin co-localized in the flagellar region of human sperm suggesting a functional relevance for SKAP1-Pontin interaction in sperm motility. Since most previous studies on SKAP were performed with the testis-specific isoform SKAP1, our findings provide a new basis for future studies on the role of SKAP in both human somatic cells and male germ cells, including studies on male fertility.

Quality Statement:

STEMCELL TECHNOLOGIES INC.’S QUALITY MANAGEMENT SYSTEM IS CERTIFIED TO ISO 13485. PRODUCTS ARE FOR RESEARCH USE ONLY AND NOT INTENDED FOR HUMAN OR ANIMAL DIAGNOSTIC OR THERAPEUTIC USES UNLESS OTHERWISE STATED.